Process for decontaminating military nerve and blister agents

ABSTRACT

The invention provides a process for decontaminating military nerve agents and blister agents. The process involves contacting the nerve agent and blister agent, particularly clothing and other items contaminated therewith, with gaseous ozone or chlorine dioxide, whereby the agents are oxidized to non-toxic products and thereby decontaminated rapidly, e.g. within a few minutes. The treatment with ozone or chlorine dioxide does not seriously affect the mechanical properties of the contaminated materials, such as fabrics.

GOVERNMENT INTEREST

The invention described herein was made in the course of or under a contract or subcontract thereunder with the Government and may be manufactured, used and licensed by or for the Government for Governmental purposes without the payment to us of any royalties thereon.

BACKGROUND OF THE INVENTION

The present invention relates to a method for decontaminating toxic chemical agents, commonly referred to as nerve agents and blister agents. These agents are of potential use in the battlefield and hence represent a serious threat to military personnel. To combat this threat various types of protective clothing and accessory equipment have been developed. However, such protective clothing and equipment must be decontaminated after they have been exposed to these chemical agents in the battlefield.

In the past the most effective methods for decontaminating such chemical agents have involved treating the contaminated items with bleach (aqueous calcium hypochlorite) or aqueous sodium hydroxide solution containing diethylenetriamine. These methods are not entirely satisfactory, since they employ solutions which are corrosive, hazardous and often have a serious adverse effect on the mechanical properties and function of the items treated. The use of steam autoclaving as well as general wet laundering and dry cleaning methods for decontaminating such items has been found costly, time consuming and impractical in certain situations and hence generally unsatisfactory. It has been reported from the Democratic German Republic that material exposed to the nerve agents Sarin and Soman can be effectively decontaminated by treatment with vapors of 10% aqueous ammonia solution; and ammonia and its derivatives, such as amines, were recommended as universal decontaminants. It has also been proposed to employ gaseous chlorine for deactivating such chemical agents but the results produced are deficient for various reasons.

An object of the present invention is to provide a process for deactivating nerve and blister agents at a rapid rate in gaseous or non-gaseous phase.

Another object of the invention is to provide a process for rapidly decontaminating clothing and other items exposed to such chemical agents without serious adverse effect on the mechanical properties of such items.

A further object of the invention is to provide a process whereby large quantities of clothing and other items contaminated with such chemical agents can be rapidly and safely decontaminated in a practical manner.

Other objects will become apparent from the following description of this invention.

SUMMARY AND DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention these objects can be accomplished by contacting nerve and blister agents with a gaseous oxidant selected from the group consisting of ozone and chlorine dioxide. The agents are thereby rapidly oxidized and converted to non-toxic products within a few minutes.

The nerve and blister agents can be treated either in the gaseous or liquid state and in the presence or absence of a substrate, such as fabrics made of cotton, rayon, wool, nylon and polyester, natural and synthetic polymers, leather, elastomers such as natural and synthetic rubber, sealants, etc.

The gaseous oxidants of the present invention are of relatively low moleular weight and possess great penetrating and permeating power into materials such as clothing and accessories and especially masses of such materials. Large quantities of clothing and other items contaminated with nerve or blister agent can be rapidly decontaminated in the field in a practical and effective manner by contacting the items with ozone or chlorine dioxide in a closed container, such as a metal tank or polyethylene tent.

The gaseous oxidants can be employed alone or in mixture with another gas or vapor, such as air or steam. These gaseous oxidants are effective in low concentrations. For example, by employing a mixture of about 1000 ppm. chlorine dioxide and about 15 ppm. mustard gas simulant in air at room temperature, a total deactivation of the simulant resulted in two minutes. The amount of gaseous oxidant of this invention required to deactivate nerve agents and blister agents varies according to the amount and nature of such chemical agent to be decontaminated.

The oxidants of the present invention, ozone and chlorine dioxide, are effective for deactivating/decontaminating nerve agents and blister agents generally. Examples of nerve agents include Sarin, Soman and VX. A typical formula for a nerve agent (VX) is as follows, viz ##STR1## Examples of blister agents include mustard (HD) and Lewisite (L).

The process of the present invention is advantageous because ozone and chlorine dioxide can be readily generated, are rapidly effective at very low concentrations and are readily removable from the decontaminated materials because they are gases. Further, they are non-corrosive and do not seriously degrade the mechanical properties of the decontaminated materials, which is important since it is essential that the structural and mechanical properties of military items, such as clothing, subjected to decontamination processes be retained as much as possible. Ozone is preferred, since it is a more powerful decontaminating gas and can be readily generated in the field by ultra violet radiation or glow discharge.

The invention is illustrated in the following examples, wherein for safety considerations half-mustard, 2-chloroethyl ethyl sulfide, was employed as the simulant for mustard gas bis(2-chloroethyl)sulfide, (agent HD) and ethyl methylphosphorofluoridate was used as the simulant for G agent, methyl isopropylphosphorofluoridate (Sarin). These simulants were selected because they are relatively non-toxic to humans and because they possess similar properties and imitate reasonably closely the response of the live nerve and blister agents. The properties of each agent and its simulant are set forth in Table 1.

Ozone, chlorine, bromine, chlorine dioxide, ammonia and other reactive gases were tested for their efficacy to deactivate the simulants in the gas phase. The more effective reactive gases were also tested for their effectiveness for decontaminating protective clothing and other military field items impregnated with the simulants. In addition, the effect of the reactive gas treatment on the material properties of the various military clothing and other items was evaluated. The military items are described in Table 2.

GAS PHASE DEACTIVATION OF SIMULANTS

The tests were carried out by injecting the reactive gas into a highly agitated dispersion of the simulant in air at room temperature and analyzing the agitated gas system to determine the reduction of simulant concentration with time by means of an infrared gas analyzer.

The test results are set forth in Tables 3 and 4, which show that ozone, chlorine dioxide, chlorine and bromine were the most effective gases employed in the gas phase deactivation of the nerve and blister agent simulants.

                                      TABLE 1                                      __________________________________________________________________________     Comparison of Agent and Simulant                                                        Agent      Simulant        Agent   Simulant                           __________________________________________________________________________     Name     Sarin      Ethyl methylphosphorofluoridate                                                                mustard (HD)                                                                           2-chloroethyl ethyl                                                            sulfide                            Structure                                                                               F(CH.sub.3).sub.2 CHOPOCH.sub.3                                                           FCH.sub.3 OPOC.sub.2 H.sub.5                                                                   (ClCH.sub.2 CH.sub.2).sub.2 S                                                          ClCH.sub.2 CH.sub.2 SCH.sub.2                                                  CH.sub.3                           State at 25° C.                                                                  liquid     --              liquid  liquid                             Boiling point, °C.                                                               147        --              227     156                                Vapor pressure at                                                                       2.20       --              0.07    3.20                               20° C., mmHg                                                            __________________________________________________________________________

                  TABLE 2                                                          ______________________________________                                         Material Items Evaluated During Program                                        Material                                                                       identification                                                                          Military                                                              No.      serial No.                                                                               Description                                                 ______________________________________                                         B485-2-1 8415-00-  outer cloth of chemical-protective suit                              407-1063                                                              B485-2-2 8415-00-  carbon urethane layer of chemical-                                   407-1063  protective suit                                             B485-2-4 8415-01-  trouser of camouflage material                                       084-1718                                                              B485-2-6 8415-01-  coat of camouflage material                                          084-1651                                                              B485-2-8 8430-01-  chemical-protective footwear covers                                  021-5978                                                              B485-2-10                                                                               8415-01-  chemical-protective glove set                                        033-5978                                                              B485-2-12                                                                               8305-00-  textile webbing                                                      148-9740                                                              B485-2-14                                                                               --        butyl-coated cloth                                          B485-2-16                                                                               --        Nomex cloth                                                 B485-2-18                                                                               --        canvas                                                      ______________________________________                                    

                  TABLE 3                                                          ______________________________________                                         Gas-Phase Reactivity of Candidate Gases with Half-Mustard                                                                %                                                       Initial  Elapsed                                                                               Final  Re-                                  Candidate  Gas,    simulant,                                                                               time,  simulant,                                                                             duc-                                 gas        ppm     ppm      min    ppm    tion                                 ______________________________________                                         Ammonia    1000    21.12    38     18.73   11                                  Methylamine                                                                               .sup. N/T.sup.a                                                     Ethylamine N/T                                                                 Dimethylamine                                                                             1000    13.55    10     14.59   0                                   Ozone      N/T                                                                 Chlorine   1000    14.02    1      0      100                                  Bromine    1000    15.41    3      0      100                                  Chlorine Dioxide                                                                          1095    15.25    2      0      100                                  Hydrogen Sulfide                                                                          1000    25.40    89     18.34   28                                  Ethanethiol                                                                    C-.sup.b                                                                       Dimercaprol                                                                                975    15.25    14     14.39   6                                   Propionaldehyde                                                                           1071    21.01    16     20.82   1                                   Formaldehyde                                                                              1205    14.65    17     14.06   4                                   Ethylene Oxide                                                                            1000    19.83    73     18.72   11                                  ______________________________________                                          .sup.a "N/T" = not tested.                                                     .sup.b C-" = retention time of ethanethiol interfered with reading of          halfmustard concn.                                                       

                  TABLE 4                                                          ______________________________________                                         Gas-Phase Reactivity of Candidate Gases with Nerve Simulant                                                              %                                                       Initial  Elapsed                                                                               Final  Re-                                  Candidate  Gas,    simulant,                                                                               time,  simulant,                                                                             duc-                                 gas        ppm     ppm      min    ppm    tion                                 ______________________________________                                         Ammonia    1180    0.281    25     0.281  0                                    Methylamine                                                                               N/T.sup.a                                                           Ethylamine N/T                                                                 Dimethylamine                                                                             1180    0.285    25     0.259  9                                    Ozone      0.120   0.122    25     0.014  88                                   Chlorine   10000   0.274    35     0.134  51                                   Bromine    N/T                                                                 Chlorine Dioxide                                                                          790     0.133    30     0.085  36                                   Hydrogen Sulfide                                                                          10.sup.6                                                                               0.176    25     0.136  22.7                                 Ethanethiol                                                                               1787    0.154    30     0.126  18                                   Dimercaprol                                                                               N/T                                                                 Propionaldehyde                                                                           1830    0.127    30     0.127  0                                    Formaldehyde                                                                              1760    0.166    25     0.166  0                                    Ethylene Oxide                                                                            5000    0.172    25     0.172  0                                    ______________________________________                                          .sup.a "N/T" = not tested.                                               

DECONTAMINATION OF MILITARY MATERIALS

Samples of each military material were cut into one inch squares and each sample was placed in a 50 cc serum vial, which was then sealed. The samples and controls were carried out in triplicate. Each sample and control was inoculated with the liquid simulant by means of a hypodermic syringe, which was employed to penetrate the vial septum and apply the simulant directly onto the surface of the test samples as well as the control samples. The materials were then allowed to equilibrate for one hour, after which the control samples were extracted with either 5 mL of cyclohexane or 5 mL of methanol. The test samples were removed from the vial and placed in a larger exposure chamber containing the decontaminating gas at a specified concentration. After a one hour exposure period the test samples were degassed by venting the exposure chamber and then extracted in the same manner as the control samples. The concentration of simulant in the extract was determined by gas chromatography (GC).

Tables 5 to 8 set forth the test results comparing the effectiveness of the gases to decontaminate the various military items contaminated with the simulants, as measured by the reduction in active extractable simulant. The tables indicate the types of material used, the amounts and types of simulants and decontaminating gas employed and the reduction in simulant concentration after the one hour exposure period.

The results show that ozone was generally highly effective for decontaminating material contaminated with either blister agent or nerve agent simulant, while chlorine dioxide was generally similarly effective for decontaminating material containing blister agent simulant but less effective for decontaminating material containing nerve agent simulant. The results also show that ozone and chlorine dioxide are significantly superior to chlorine and bromine for deactivating the agent simulants. Thus, as is evident from Table 6, approximately 0.6×10⁻⁶ moles of chlorine dioxide and approximately 8×10⁻⁶ moles of ozone were effective for deactivating 8.55×10⁻⁶ moles of agent simulant, whereas approximately 6×10⁻⁴ moles of chlorine and approximately 1×10⁻⁴ moles of bromine were required to deactivate the same amount of agent simulant, as shown in Table 5.

EFFECT OF DECONTAMINATING GASES ON MECHANICAL PROPERTIES OF MILITARY CLOTHING AND OTHER ITEMS

To determine the effect of the reactive gas treatment on the decontaminated items, the fabric samples were exposed to the reactive gases under conditions similar to those used to accomplish effective decontamination of samples contaminated with the aforesaid simulants. The samples were then degassed and the mechanical properties of the gas treated items and corresponding untreated items were determined by means of an Instron Model TMS instrument. The results are set forth in Tables 9 and 10 which indicate the type of material treated, the type and concentration level of decontaminating gas employed, and the reduction in tensile strength of the material resulting from the gas treatment. A comparison of the data set forth in these tables shows that the treatment with ozone did not seriously affect the strength of the clothing and other materials treated.

                                      TABLE 5                                      __________________________________________________________________________     Effectiveness of Chlorine and Bromine in Decontaminating                       Materials Spiked with Half-Mustard                                             Material         Amount of decontaminating gas,                                                                 Decontamination effectiveness                 identification                                                                        Amount of simulant,                                                                      moles × 10.sup.4                                                                         reduction in simulant,                                                                        Exposure                       No.    moles × 10.sup.6                                                                   Cl.sub.2                                                                               Br.sub.2                                                                               Cl.sub.2                                                                              Br.sub.2                                                                               period,                        __________________________________________________________________________                                                     hr                             B485-2-1                                                                              8.55      5.97    1.16    100    100     1                              B485-2-2                                                                              8.55      5.97    1.16    25     91      1                              B485-2-4                                                                              8.55      5.97    1.16    100    100     1                              B485-2-6                                                                              8.55      5.97    1.16    100    100     1                              B485-2-8                                                                              8.55      5.97    1.16    73     75      1                              B485-2-10                                                                             8.55      5.97    1.16    56     40      1                              B485-2-12                                                                             8.55      5.97    1.16    77     100     1                              B485-2-14                                                                             8.55      5.97    1.16    67     85      1                              B485-2-16                                                                             8.55      5.97    1.16    92     100     1                              B485-2-18                                                                             8.55      5.97    1.16    92     100     1                              __________________________________________________________________________

                                      TABLE 6                                      __________________________________________________________________________     Effectiveness of Chlorine Dioxide and Ozone in Decontaminating                 Materials Spiked with Half-Mustard                                             Material         Amount of decontaminating gas,                                                                 Decontamination effectiveness                 identification                                                                        Amount of simulant,                                                                      moles × 10.sup.6                                                                         reduction in simulant,                                                                        Exposure                       No.    moles × 10.sup.6                                                                   ClO.sub.2                                                                              O.sub.3 ClO.sub.2                                                                             O.sub.3 period,                        __________________________________________________________________________                                                     hr                             B485-2-1                                                                              8.55      0.614   8.21    100    100     1                              B485-2-2                                                                              8.55      0.614   8.21     50    6.6     1                              B485-2-4                                                                              8.55      0.614   8.21    100    100     1                              B485-2-6                                                                              8.55      0.614   8.21    100    100     1                              B485-2-8                                                                              8.55      0.614   8.21    100    92      1                              B485-2-10                                                                             8.55      0.614   8.21    100    84      1                              B485-2-12                                                                             8.55      0.614   8.21    .sup. --.sup.a                                                                        100     1                              B485-2-14                                                                             8.55      0.614   8.21    --     100     1                              B485-2-16                                                                             8.55      0.614   8.21    --     100     1                              B485-2-18                                                                             8.55      0.614   8.21    --     93      1                              __________________________________________________________________________      .sup.a "--" = not evaluated.                                             

                                      TABLE 7                                      __________________________________________________________________________     Effectiveness of Chlorine Dioxide and Ozone in Decontaminating                 Materials Spiked with G-Analog                                                 Material         Amount of decontaminating gas,                                                                 Decontamination effectiveness                 identification                                                                        Amount of simulant,                                                                      moles × 10.sup.6                                                                         reduction in simulant,                                                                        Exposure                       No.    moles × 10.sup.5                                                                   ClO.sub.2                                                                              O.sub.3 ClO.sub.2                                                                             O.sub.3 period,                        __________________________________________________________________________                                                     hr                             B485-2-1                                                                              1         0.614   8.21    33     92      1                              B485-2-2                                                                              1         0.614   8.21    68     8.3     1                              B485-2-4                                                                              1         0.614   8.21    13     91      1                              B485-2-6                                                                              1         0.614   8.21    13     91      1                              B485-2-8                                                                              1         0.614   8.21    37     92      1                              B485-2-10                                                                             1         0.614   8.21    51     58      1                              B485-2-12                                                                             1         0.614   8.21     0     89      1                              B485-2-14                                                                             1         0.614   8.21    18     100     1                              B485-2-16                                                                             1         0.614   8.21    39     100     1                              B485-2-18                                                                             1         0.614   8.21    47     42      1                              __________________________________________________________________________

                                      TABLE 8                                      __________________________________________________________________________     Effectiveness of Chlorine and Bromine in Decontaminating                       Materials Spiked with G-Analog                                                 Material         Amount of decontaminating gas,                                                                 Decontamination effectiveness                 identification                                                                        Amount of simulant,                                                                      moles × 10.sup.4                                                                         reduction in simulant,                                                                        Exposure                       No.    moles × 10.sup.5                                                                   Cl.sub.2                                                                               Br.sub.2                                                                               Cl.sub.2                                                                              Br.sub.2                                                                               period,                        __________________________________________________________________________                                                     hr                             B485-2-1                                                                              1         4.08    1.16    27     59      1                              B485-2-2                                                                              1         4.08    1.16     0      0      1                              B485-2-4                                                                              1         4.08    1.16    16     19      1                              B485-2-6                                                                              1         4.08    1.16    16     19      1                              B485-2-8                                                                              1         4.08    1.16    75     89      1                              B485-2-10                                                                             1         4.08    1.16    77     94      1                              B485-2-12                                                                             1         4.08    1.16     0     12      1                              B485-2-14                                                                             1         4.08    1.16    --.sup.a                                                                              --      --                             B485-2-16                                                                             1         4.08    1.16    13     71      1                              B485-2-18                                                                             1         4.08    1.16    44     48      1                              __________________________________________________________________________      .sup.a "--" = not evaluated.                                             

                                      TABLE 9                                      __________________________________________________________________________     Effect of Candidate Gases on Tensile Strength of Combat Materials              10,000 ppm Cl.sub.2, 1 hr                                                                      10,000 ppm Cl.sub.2, 16 hr                                                                100,000 ppm Cl.sub.2, 1 hr                                                                10,000 ppm Br.sub.2, 1                                                                   8 ppm O.sub.3, 40 min          Sample No.                                                                           Mean SD   Mean  SD   Mean SD    Mean SD   Mean                                                                               SD                         __________________________________________________________________________     B425-2-1                                                                             7,090                                                                               202  .sup. N/T.sup.a                                                                      --   11,490                                                                              540   6,580                                                                               466  3,768                                                                              109                        B485-2-2                                                                               980                                                                                16  N/T   --   1,130                                                                                37     984                                                                               146    821                                                                               68                        B485-2-4                                                                             9,390                                                                               223  10,380                                                                               575  N/T  --    12,010                                                                              1,168                                                                               11,313                                                                             503                        B485-2-6                                                                             9,390                                                                               223  N/T   --   N/T  --    12,010                                                                              1,168                                                                               --  --                         B485-2-8                                                                             1,300                                                                               101  N/T   --   N/T  --    1,300                                                                                43  1,006                                                                               42                        B485-2-10                                                                            1,640                                                                                84  N/T   --   1,520                                                                               120   1,560                                                                                33  1,419                                                                              240                        B485-2-12                                                                            50,000                                                                              2,133                                                                               N/T   --   N/T  --    48,670                                                                              2,800                                                                               48,862                                                                             1,606                      B485-2-14                                                                            8,110                                                                               831  N/T   --   N/T  --    8,170                                                                               562  10,752                                                                             689                        B485-2-16                                                                            14,910                                                                              830  N/T   --   8,960                                                                               1,360 14,610                                                                              507  7,994                                                                              147                        B485-2-18                                                                            8,920                                                                               206   8,600                                                                               873  7,700                                                                               634   7,780                                                                               631  6,434                                                                              303                        __________________________________________________________________________      .sup.1 "N/T" = not tested.                                               

                                      TABLE 10                                     __________________________________________________________________________     Mechanical Properties of Untreated Materials                                   Notebook                                                                             Serial           Density,                                                                            Fiber count                                                                          Tensile strength, psi                        No.   No.  Description oz/yd.sup.2                                                                         warp                                                                              fill                                                                              warp fill                                    __________________________________________________________________________     B485-2-1                                                                             8415-00-                                                                            Outer cloth-layer of                                                                       5.93 50 88 7230 13650                                         407-1063                                                                            chemical-protective                                                            suit                                                                B485-2-2                                                                             8415-01-                                                                            Carbon/urethane layer                                                                      7.89 --.sup.a                                                                          --.sup.a                                                                          1110 --.sup.a                                      084-1063                                                                            of protective suit                                                  B485-4                                                                               8415-01-                                                                            Camouflaged pants                                                                          7.77 56 88 11730                                                                               14400                                         084-1718                                                                 B485-6                                                                               8415-01-                                                                            Camouflaged coat                                                                           7.77 56 88 11730                                                                               14400                                         084-1651                                                                 B485-8                                                                               8430-01-                                                                            Chemical-protective                                                                        0.59.sup.b                                                                          --.sup.a                                                                          --.sup.a                                                                          1170 --.sup.a                                      021-5978                                                                            footwear covers                                                     B485-10                                                                              8415-01-                                                                            Chemical-protective                                                                        0.65.sup.b                                                                          --.sup.a                                                                          --.sup.a                                                                          1730 --.sup.a                                      033-5978                                                                            glove set                                                           B485-12                                                                              8305-00-                                                                            Textile webbing  --.sup.a                                                                          --.sup.a                                                                          --.sup.c                                                                            --.sup.a                                      148-9740                                                                 B485-14                                                                              --   Butyl-covered cloth                                                                        8.99 --.sup.d                                                                          --.sup.d                                                                          8430  8760                                   B485-16                                                                              --   Nomex cloth 14.87                                                                               68 48 13010                                                                               10810                                   B485-18                                                                              --   Canvas      17.40                                                                               24 28 9150  6780                                   __________________________________________________________________________      .sup.a No warp or fill.                                                        .sup.b A solid material. The units are oz/in.sup.3.                            .sup.c The fiber the webbing is made of was tested.                            .sup.d No fiber count could be taken. The length of the fiber roll was         called warp.                                                              

We claim:
 1. In an improved process of decontaminating large quantities of protective clothing without substantially degrading said clothing, said clothing having been exposed to chemical warfare simulants, comprising: contacting said clothing for penetration and permeation with chlorine dioxide, a gaseous decontaminant, and degassing said decontaminant from said clothing.
 2. The process of claim 1 wherein said clothing is made of a material or mixture selected from the group consisting of cotton, rayon, wool, nylon, polyester, natural polymers, synthetic polymers, leather, elastomers, natural rubber, synthetic rubber, and sealants.
 3. The process of claim 1 wherein said chemical warfare simulants are 2-chloroethyl ethyl sulfide and ethyl methylphosphorofluoridate. 